Changing of macronutrients in leaves in yearly growth stages of pummelo
2017
Isarangkool Na Ayuttaya, S. | Yangyuen, P. | Songsri, P. | Meetha, S. | Techawongstein, S.
The experiment was conducted to investigate the changes of five macronutrients in leaves including nitrogen (N), phosphorus (P), potassium (K), calcium (Ca), and magnesium (Mg) in different growth stages of pummelo (Citrus maxima Merr.). The work was done in 4 farmer's orchards (4 replications) located in Bantan district, Chaiyaphum province, Thailand. Five trees in each orchard were selected for replication. Typical growth stages of pummelo in this area are 1) vegetative phase during the end of August to November; 2) induced flowering by water shortage in early December; 3) flowering in mid-January to early February; and 4) harvesting in July to August. The results showed that the P content was highest in the floral development to bud bursting stage, December-February (P‹0.001), while N content was not significantly different in all growth stages. The following immobile nutrient (Ca) in the same leaf flushing set found that the Ca content increased according to leaf age. However, Ca content was highest before flowering. Therefore, the optimum period for leaf sampling should be at 4 to 5 months after flowering. Additionally, the range of N, P, K, Ca and Mg content in the four orchards were 2.47-2.77, 0.14-0.23, 1.73-3.64, 1.43-3.31 and 0.14-0.29%, respectively.
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